Lecture 3A: Respiration Flashcards
Energy Production and Primary Metabolism
What is catabolism?
Breakdown of complex molecules
What do chemoorganotrophs obtain energy from?
Organic compounds
Organisms that obtain energy by oxidizing organic compounds and use them as both a source of energy and carbon are called __ (or __). Examples of organic compounds they utilize include: (4)
- chemoheterotrophs
- chemoorganotrophs
- Examples:
Carbohydrates (e.g., glucose, sucrose, starch)
Lipids (e.g., fatty acids, triglycerides)
Proteins (e.g., amino acids)
Nucleic acids (e.g., DNA, RNA components)
Fermentation occurs in the absence of what?
Oxygen
Does fermentation require an external electron acceptor?
No
What are the two types of respiration? (2)
Anaerobic and aerobic
What is the electron acceptor in aerobic respiration?
Oxygen
Give an example of an electron acceptor in anaerobic respiration. (2)
Nitrate (NO3^-) and sulfate (SO4^2-)
What is another name for glycolysis?
Embden-Meyerhof-Parnas pathway
What is glucose oxidized to in glycolysis?
Pyruvate
Is glycolysis found in both fermentation and respiration?
Yes
How many redox reactions occur in glycolysis?
Two
What type of phosphorylation produces ATP in glycolysis?
Substrate-level phosphorylation
What happens to pyruvate in respiration?
Further oxidized to CO₂
What happens to pyruvate in fermentation?
Used as an electron acceptor
What is the main electron acceptor in fermentation?
Internal organic molecules
What is the main electron acceptor in respiration?
External molecules (inorganic or organic)
Which pathway involves complete oxidation of the electron donor?
Respiration
What is the purpose of Stage I of glycolysis?
Prepare glucose for breakdown
Recite Glycolysis: Stage I: Preparatory Reactions (Energy Investment): Include the chemicals, chemical reactions, enzymes, ATP produced, and byproducts involved.
Glucose phosphorylation (first step):
- Reaction: Glucose → Glucose 6-phosphate
- Enzyme: Hexokinase (or Glucokinase in the liver)
- Use 1 ATP
Isomerization:
- Reaction: Glucose 6-phosphate → Fructose 6-phosphate
- Enzyme: Phosphoglucose isomerase
Phosphorylation of fructose 6-phosphate:
- Reaction: Fructose 6-phosphate → Fructose 1,6-bisphosphate
- Enzyme: Phosphofructokinase-1 (PFK-1)
- Use 1 ATP
Splitting of fructose 1,6-bisphosphate:
- Reaction: Fructose 1,6-bisphosphate → glyceraldehyde-3-phosphate (G3P) + Dihydroxyacetone phosphate (DHAP)
- Enzyme: Aldolase
Conversion of DHAP:
- Reaction: Dihydroxyacetone phosphate (DHAP) → glyceraldehyde-3-phosphate (G3P)
- Enzyme: Triose phosphate isomerase
What are the two products of fructose 1,6-bisphosphate splitting? (2)
- Dihydroxyacetone phosphate (DHAP)
- glyceraldehyde-3-phosphate (G3P)
Which molecule is Dihydroxyacetone phosphate (DHAP) converted into? Which enzyme catalyzes this reaction?
- glyceraldehyde-3-phosphate (G3P)
- Triosephosphate isomerase
How many ATP molecules are consumed in Stage I of glycolysis?
2 ATP
Do redox reactions occur in Stage I of glycolysis?
No